1. Field of the Invention
The present invention relates to a process for conversion of soluble biodegradable organic compounds into useful products. The process of the invention converts such soluble biodegradable organic compounds into useful products, such as, high protein concentrates for animal fodder and sources of protein, enzymes and vitamins. The process of the invention can be used for treating certain food processing wastes and for treating certain industrial wastes.
2. Description of the Prior Art
Municipal sewage generally contains about 100 to 300 mg/l solubles and about 100 to 500 mg/l solids and the treatment in a municipal sewage plant is to break down and remove both solubles and solids. The predominant problem, however, with municipal sewage treatment is to remove the solids and since the amount of solubles present in material to be treated generally is minor, there is little concern with the solubles present. In contrast, biodegradable industrial wastes generally contain about 1000 to 100,000 mg/l. For example, cheese whey has a solubles content of about 60,000 mg/l and only a trace of solids.
Industrial wastes in this form cause extreme problems and upsets to sewage treatment plants because of the high concentration of waste and as a result of the high level, the material must either be treated prior to treatment by municipal sewage treatment plants or disposed of using alternative methods. Conventional treatment of industrial wastes is dilution with water and then to treat the diluted wastes in the same manner as municipal sewage or simply disposal by injecting of the waste into deep wells. These wastes are not, therefore, recovered.
Present day conventional methods for treatment of municipal sewage wastes generally containing a large solids content and minor amounts of solubles on a relative basis are based upon subjecting the wastes to microbial oxidation by the activated sludge process. Activated sludge and flocculated waste generally has a solids content of about 200,000 mg/l and in the activated sludge process used to treat such wastes up to 90% of the organic material is removed as a solid residue or a semi-solid sludge. The sludge and flocculated wastes are stabilized in an anaerobic digester for about 30 days. The waste then must be disposed of by such methods as use as land fillings, disposal at sea, incineration, further treatment to produce fertilizers, and use in soil conditioning, etc. Where the product is to be used as a land fill, additional problems arise due to the presence of pathogenic organisms and generally thermophilic conditions are employed in the digester to destroy pathogenic bacteria. Due to environmental concerns of space limitations, of odors and air quality, of problems with pathogenicity, the above methods of disposal are expensive and environmentally of concern. Therefore, at the present time, there is great interest and activity in research on waste treatment methods.
For example, U.S. Pat. No. 3,462,275 discloses a process in which solid, organic biodegradable wastes such as solid sludge from primary sewage treatment plants, activated sludge from secondary sewage treatment plants, and solid wastes obtained by coagulation or flocculation of dilute aqueous waste containing suspensions, i.e., coagulation or flocculation is used since the solid materials have about the same specific gravity as the medium and do not settle, are treated with mixed populations of selected thermophilic microorganisms under aerobic conditions at temperatures of from 45.degree. to 80.degree.C. Cellular proteinaceous materials and other cellular products are disclosed as being produced by the above-described process. The emphasis in this process is the treatment of solid waste materials, i.e., sewage sludge, activated sludge, animal wastes containing about 20% by weight solids with low solubles levels or the concentration by flocculation of dilute suspensions of solid wastes and the utilization of organisms and conditions which promote the breakdown or organic polymers such as cellulose materials, the fungi present in such a mixed population being so favored and producing cellular proteinaceous material and products which, due to their nature, are useful as feeds only for ruminants or must be further processed for ready availability by other animals by extraction of the crude proteins with hot alkali followed by purification.
The above-described process is not and the prior art in general has not been concerned with the problems of soluble biodegradable organic waste materials present, for example, in food processing wastes, e.g., various types of cheese whey, and in industrial waste solutions such as those generated in the petroleum and photographic industries, these materials comprising generally soluble organic waste materials. These materials generally contain soluble wastes dissolved in solution and at concentrations which are sufficiently high to cause environmental problems if discharged directly into the biosphere and generally cause severe treatment problems if not pretreated, e.g., by dilution with water, if fed directly to solid waste treatment plants.
It is an object of this invention to provide a waste treatment method for disposing of food processing wastes and industrial biodegradable wastes.
It is also an object of this invention to provide a process for producing proteins, vitamins, enzymes and unidentified growth factors from sources of soluble biodegradable waste materials.
It is additionally an object of this invention to provide a process for producing proteins from such soluble wastes in a high yield.
It is another object of this invention to provide a process for producing a source of proteins as animal feeds and feed supplements which can be readily utilized and metabolized by a wide variety of animals without the need for further significant treatment or processing.
It is a further object of this invention to provide a method of producing from soluble biodegradable waste materials an effluent low in biochemical oxygen demand, low in nitrogen, and low in phosphorus which meets present Federal Environmental Water Quality Standards in most locations and can be discharged directly into rivers and streams without causing pollution problems or which can be discharged through conventional municipal sewage systems without providing an unreasonable load to such sewage systems.
These and other objects of the invention are obtained in the practice of the process of this invention as hereinafter described.